Chair control

ABSTRACT

1,160,634. Seats. KNOLL ASSOCIATES, Inc. 21 July, 1967 [2 Aug., 1966], No. 33778/67. Heading A4J. In a tilting office chair, having a hollow support column 8, housing vertical springs 53, 54 or a stack of resilient conical washers, a lever 40 is mounted on a pivot 32 and is adjustable to pre-stress the springs. Metal bracket 5a is formed, by die-casting, about the head 20, of adjustment screw 19. On tilting the chair rearwardly, the springs are compressed but prevented from contacting the metal column 8, by plastic liner 55. The tilting is limited by stop 18 engaging flange 27a.

Dec. 24, 1968 c. R. HELMS 3,417,956

CHAIR CONTROL I Filed Aug. 2, 1966 2 Sheets-Sheet 2 ATTO RNEV 3,417,956 CHAIR CONTROL Charles Robert Helms, East Greenville, Pa., assignor to Art Metal-Knoll Corporation, a corporation of Delaware Filed Aug. 2, 1966, Ser. No. 569,640 8 Claims. (Cl. 248379) ABSTRACT OF THE DISCLOSURE A chair control mechanism for controlling tilting movement of a chair seat from a horizontal position, wherein the support column includes a pivot bracket having spaced vertical arms, said chair seat includes a mounting bracket including a second pair of spaced vertical arms, a control means comprising a pair of lever arms, a pivot pin pivotally mounting said first and second pair of vertical arms and said pair of lever arms, adjustment means mounted on the mounting bracket comprising a threaded stud fixedly mounted to the mounting bracket and a handwheel threadedly engaged on the stud and rotatable to vary the position of the second lever arm, and resilient means engaging the first lever arm and referencing it to the support column.

Chair control mechanisms for controlling the degree of opposition to tilting movement, e.g. for controlling spring tension, are known. The standard chair control mechanisms include exposed parts, such as springs and brackets, immediately under the upper seat portion. These parts are unsightly, and also cause practical difficulties such as snagging or dirtying of the clothes of the occupant. In recent years, design trends and the commercial requirements of the market have demanded chairs whose appearance is unmarred by such unsightly exposed mechanical parts. The art has seen various attempts to devise a practical chair control mechanism without exposed parts other than an adjustment lever, wheel, or knob. While it is not difiicult to design an enclosed chair control mechanism per se, and such has been done, until now an enclosed chair control mechanism of simple, rugged, and mechanically efficient construction has eluded the art. That is to say, chair control mechanisms enclosed within the normal contours of the chair have, until the present invention, been compromised mechanically because of the necessary constriction and rearrangement of parts.

It is an object of the invention to provide a chair control mechanism in which the mechanical parts thereof, other than the manual adjustment knob or the equivalent, are substantially entirely enclosed within the contours of the chair so as to be concealed from view, and are sensitive, efficient, and accurate in operation and adjustment by said knob or equivalent.

Another object of the invention is to provide an improved chair control mechanism of simplified and compact construction.

Another object of the invention is to provide a chair control mechanism characterized by improved ease of adjustment of the tilting resistance of the chair.

In accordance with the invention, the chair control includes a tubular column carrying the chair seat at its upper end and having its lower end telescopingly received within a hub forming part of the chair base. A supporting pan rigidly secured to the chair seat is pivotally mounted on a bracket rigidly connected to the top of the column to provide tilting movement of the chair relative to the column. The column includes a housing for receiving and supporting the lower end of a coil spring. The upper end of the spring is engaged by a lever pivotally mounted on the mounting bracket for movement therewith, the coil United States Patent Patented Dec. 24, 1968 spring yieldingly opposing tilting movement of the chair seat. The opposite end of the lever is adjustable relative to the mounting bracket to adjust the initial compression of the coil spring.

For a better understanding of the invention, reference may be had to the following detailed description and drawings, in which like elements are indicated by like numerals and in which:

FIG. 1 is a front elevational view of a portion of a chair incorporating the improved chair control mechamsm;

FIG. 2 is a sectional view on the line 2-2 of FIG. 1 and shows details of the chair control mechanism;

FIG. 3 is a top plan view of a seat supporting pan and shows certain of the elements of the chair control mechanism of FIGS' 1 and 2;

FIG. 4 is a perspective fragmentary view of the seat supporting pan shown partly in section along the line 22 of FIG. 1;

FIG. 5 is a perspective fragmentary view of a chair support column and bracket also shown in FIGS. 2 and 3; and

FIG. 6 is an exploded perspective view of a control lever and a plunger also shown in FIGS. 2 and 3.

FIG. 1 shows a fragmentary view of a chair seat indicated generally at 1, which includes a seat supporting pan 5, and which is tiltably mounted upon a supporting base 2 by an intermediate chair control mechanism indicated generally at 3, which mechanism is manually operable by a handwheel 4. For purposes of this specification, chair seat 1 is any seat member attached to pan bracket 50. Pan 5 may be considered the chair seat, although padding or the like, or other structure, may be supported by pan 5. Consequently, the general reference to chair seat 1 is made herein, but reference to pan 5 will be equivalent thereto. The chair control mechanism 3 includes a pan bracket 5a secured to the pan 5 by suitable means, such as screws 6. The seat 1 is thereby pivotally connected through pan bracket 5a to a column 8 as more fully described below. The chair control mechanism 3 yieldingly opposes tilting movement of the chair seat 1 relative to the column 8, and such opposition is adjustable by means of handwheel 4. The tubular column 8 is telescopingly received within a tubular hub 9 which is rigidly connected to, and may comprise part of the supporting base 2.

FIG. 1, in showing the external outline of the chair control mechanism 3, clearly illustrates the compactness thereof and the way in which the mechanism 3 is integrated into the normal outline of the chair. It is also apparent that the component elements of the invention are either enclosed or substantially concealed from view; as a result, the mechanisms are very neat in appearance and protected from contact with the occupants clothing.

In FIGS. 2 to 6 are shown various views of elements according to the invention, in each case oriented such that the left hand side in each figure represents the rear, and the right hand side represents the front, respectively, of the chair control mechanism 3 when attached to chair seat 1.

Referring to FIGS. 2 and 4, the pan bracket 5a includes a peripheral mounting flange 5b in which apertures 50 are provided for receiving the screws 6. The pan 5, with the chair seat 1 therein, may thereby be secured rigidly to pan bracket 5a. Preferably, the pan bracket 5a is cast in a metal, such as iron, although it may equally well be cast or otherwise formed from other metals.

Inward of a pair of opposed edges of flange 5b is a corresponding pair of depending, substantially parallel side portions 10, formed integrally with flange 5b, and including a pair of transverse, axially aligned apertures 11 for pivotal connection of the pan bracket 5a to the support column 8, as will presently be described. Preferably, the side walls 10 include thickened sections 12 surrounding the apertures 11 to provide increased strength. A pair of horizontal, inwardly extending side flanges 13 are integrally formed at the bottom edges of the side walls 10, and a contoured front wall 14 extends between the side walls 10 and integrally joins the side flanges 13 to an inward edge of the peripheral flange b at the front end of the bracket. An elongated slot 140 is formed in the center of the front wall 14, extending from the bottom edge of wall 14 to the flange 5b.

An interior, rear wall 16 extends between the side walls and includes thickened end sections 16a (only one of which is shown) integral with the rear edges of the side flanges 13. An exterior, contoured rear wall 17 extends between the side walls 10 and joins the bottom edge of the rear wall 16 to an inward edge of the flange 5b at the rear of the pan bracket 5:2. It is preferred, for increased strength, that ribs 15 be formed joining the interior rear wall 16 to the exterior rear wall 17 and to the adjacent inward edge of the flange 517. A lip 18 is formed integrally with the interior rear wall 16 and extends inwardly at a slightly depending angle from the flange 5b. The lip 18 serves as a rear limit stop, or back stop, to limit the maximum angle of rearward tilting of the chair, in a manner presently to be described.

A threaded shaft 19 is mounted within the front portion of flange 51), extending vertically downward in a generally perpendicular relationship to the plane of the flange 5b. The shaft 19 is preferably formed of steel and includes an enlarged head 20. The shaft 19 conveniently may be rendered integral with the pan bracket 5a by suitably supporting the head 20 within a die (not shown) in which the pan bracket 5a is cast such that it will be encased and surrounded by the metal of the flange 5!). Alternatively, an elevator bolt (not shown) may be employed, and in this instance the bolt will be inserted in a hole (not shown) in pan bracket 50, with the enlarged head rotatably captured (e.g. by having a flat thereon, or by being hexagonal, etc.) in a concentric depression (not shown) in pan bracket 5a. This avoids the necessity of casting-in shaft 19.

The pan bracket 5a thus defines an aperture or inlet 21 which is surrounded by the horizontal flanges 13 on the sides, the contoured wall 14 at the front, and the interior rear wall 16 at the rear. The aperture 21 provides an inlet into the interior of the bracket 5a for receiving a top end of the column 8 to which the pan bracket 5a is pivotally connected. The elongated slot 14a in the contoured front wall 14 communicates with the aperture 21 and the interior of the bracket 5:: for a purpose presently to be described.

As is best shown in the perspective view of FIG. 5, a pivot bracket 25 includes a pair of spaced vertical arms 26 joined by an integral, horizontal web 27. An aperture 28 is provided in the web 27 for receiving the column 8, and the web 27 is welded to the column 8, as indicated at 29 (FIG. 2). A pair of apertures 30 are provided in the arms 26 and aligned along a horizontal axis, and a pair of hardened bushings 31 are received in the apertures 30.

Referring concurrently to FIGS. 2 and 3, the pan bracket 5a is pivotally connected to the support column 8 for tilting movement of the chair seat 1 relative to the column 8. A pivot pin 32 is rotatably mounted in the bearings 31 in the vertical arms 26 of bracket 25 and is received through the aperture 11 in the side walls 10 of pan bracket 5a to provide the pivotal connection.

A control member 34, shown in perspective in FIG. 6, includes an aperture 35 in a central portion thereof by which it is mounted on the pivot pin 32. The control member 34 includes a threaded aperture 36, the axis of which is transverse to and intersects the axis of the aperture 35, for receiving a set screw 37. The pivot pin 32 includes an indent or a flattened surface 32a (FIG. 2)

which is engaged by the set screw 37 to secure the pivot pin 32 and the control member 34 together and against relative rotation. The control member 34 comprises a first lever arm 39 and a second lever arm 40 which extend outwardly from the central portion at aperture 35. The end of the first lever arm 39 includes a transverse groove recess 41 and the end of the second lever arm 40 is bifurcated to form an elongated slot 42.

A plunger 43, also shown in perspective in FIG. 6, cooperates with the control member 34 and includes a horizontal, circular plate 44, an upper tongue member 45 having a convex upper extremity 46, and a lower, axially aligned shaft 47. The plunger 43 is received within the column 8 in axial alignment, the tongue member 45 extending above the top of the column 8.

The first lever arm 39 extends rearwardly to position the groove recess 41 in axial alignment with the tongue 45 of plunger 43, the recess 41 of lever arm 39 receiving the convex upper extremity 46 of the tongue 45 in mating relationship. The mating surfaces 41 and 46 undergo a very slight relative motion during tilting movement of the chair, as will be described shortly. The second lever arm 40 extends through the slot 14:: in the front wall 14 of pan bracket 5a and the slot 42 is received over the threaded shaft 19 with the bifurcated end portion resting on the handwheel 4.

The column 8 is indented or otherwise formed to include an annular instep 50 intermediate its upper and lower ends. A retainer plate 51 is received diametrically within the column 8 and includes an annular shoulder 51a to facilitate seating on the instep 50. If desired, the retainer plate 51 may be welded to the column 8, although this is not necessary.

The retainer plate 51 defines a housing 52 within the upper portion of the column 8. Resilient means is received in the housing 52 and preferably comprises a light weight, inner coil spring 53 and a coaxial, heavier weight, outer coil spring 54. As an alternative to the coil springs 53 and 54, any suitable resilient means, such as an axially aligned stack of conical washers, or the like, may be employed.

Preferably, a cylindrical sleeve 55 of plastic or other suitable material is received within the housing 52 in close engagement with the interior cylindrical walls of the column 8 to prevent direct metal to metal contact of the spring with the column wall. In addition, the housing may be lubricated to assure continued durability and quiet operation of the springs 53 and 54. The coil springs 53 and 54 are finished on their end surfaces, as indicated at 53a and 54a to seat on the retainer plate 51 and, as indicated at 53b and 54b, to seat on the plate 44 of the actuating member 43. The lower shaft 47 extends into the inner coil spring 53 and assists in maintaining both springs 53 and 54 in axial alignment within the housing 52.

In operation, during tilting movement of the chair seat 1, the control member 34 is held by the handwheel 4 on shaft 19 in fixed relationship to the pan bracket 5a for common rotation with the pivot pin 32 relative to the bracket 25 (within the bushings 31) and the column 8. During tilting, the first lever arm 39 of the control member 34 forces the plunger 43 axially downwardly, the mating surfaces 41 and 46 undergoing slight relative motion to provide for transferring the arcuate motion of the control member 34 to axial motion of the plunger 45. The relative motion of these surfaces is very slight and by suitable choice of materials and lubricants, does not result in any wearing of these elements. Since the surfaces are entirely enclosed within the pan bracket 5a, there is no possibility of the lubricant coming into contact with the occupant of the chair.

The coil springs 53 and 54 resiliently oppose downward axial displacement of the plunger 45, thereby yieldingly opposing tilting movement of the pan bracket 5a with chair seat 1 relative to the column 8. The rearward tilting of chair seat 1 is ultimately limited by abutment of lip 18 against rear flange portion 27a of the web 27. The springs 53 and 54 are chosen to be stifl? enough to prevent tilting of the chair seat 1 to such an extent under normal conditions, but the rear stop provided by lip 18 and flange portion 27a insures against an occupant being injured should the tension mechanism be improperly adjusted or should too great a load be placed in the chair seat 1.

The springs 53 and 54 also resiliently urge the pan bracket 5a with chair seat 1 to a normal, generally horizontal position in which chair seat 1 is substantially perpendicular to the axis of column 8. When, for example, an occupant leaves the chair, the chair seat 1 will return to the generally horizontal position, and tilting forward will be limited by the engagement of flanges 13 of pan bracket 5a with the lower surfaces of the web 27 of the bracket on both sides of column S, as may be seen in FIG. 3.

The chair control mechanism may be adjusted to change the yielding opposition to tilting movement of the chair 1 by rotating handwheel 4 in one or the other direction. The greater length of the second lever arm relative to the first lever arm 39 provides a mechanical advantage, easing the rotation of handwheel 4 in efiecting the tension adjustment of springs 53, 54. Depending on the direction of rotation of handwheel 4, it is selectively axially displaced along the threaded stud 19 in a direction closer to, or farther away from, the pan bracket 5a. In changing the axial position of the handwheel 4, the control member 34 and the pivot pin 32 rotate in fixed relationship about the horizontal pivot axis, relative to both the pan bracket 5a and the pivot bracket 25; thus, the pivot pin 32 rotates within the bushings 31 and within the apertures 11. Since the rotation of the pivot pin 32 within the apertures 11 occurs only during adjustment of the chair control mechanism, there is no need to provide bearings or lubrication between their contacting surfaces.

The rotation of control member 34 on pivot pin 32 axially displaces the plunger to vary the initial compression of the coil springs 53 and 54, and thus the initial yielding opposition of the chair control mechanism 3 to tilting movement of the chair seat 1. In FIG. 2, the tension control mechanism is shown adjusted to provide a minimum yielding opposition to tilting movement. Plunger 43 is substantially at the top extreme of its travel, and the springs 53 and 54 are under a minimum of compression. To increase the tension, or yielding opposition, handwheel 4 is turned and advanced axially upwardly along the shaft 19, thereby to rotate control member 34 in a counterclockwise direction (as viewed in FIG. 2). The counterclockwise rotation of control member 34 relative to the pan bracket 5a will cause a downward axial movement of the plunger 45 into the housing 52, thereby increasing the initial compression of the springs 53 and 54 and increasing the initial tension or yielding opposition thereof to tilting movement of the pan bracket 5a. The procedure may of course be reversed to decrease the initial tension or yelding opposition to tilting movement.

The feature of concealing the coil springs or other resilient means in housing 52 within the column 8 not only improves the appearance of the chair control mechanism but also avoids exposing the springs to act as dirt collectors and thus to detract from the appearance of the furniture. Frequently, oil, grease or other lubricants are applied to the springs to ease the compression thereof and to reduce noise during tilting movement; the housing 52 therefore enables more efficient lubrication of the springs while also avoiding the possibility of the lubricated springs soiling the clothes of the occupant of the chair or otherwise detracting from the appearance of the chair.

The pan bracket 5a is contoured to provide a pleasing appearance and is compact such that it is substantially unnoticeable. Nevertheless, the tilt mechanism offers excellent yielding opposition to tilting movement and provides a firm and secure mounting of the chair seat to a support column. Adjustment of the tension is achieved with the greatest ease and conveniently may be accomplished while a person is seated in the chair. Moreover, the tilt control mechanism employs a minimum number of parts and may be manufactured at low cost.

The chair seat 1 may be rotatable on chair base 2, as well as tiltable. When the chair is constructed to include rotation as well as tilting, the relationship of column 8 to tubular hub 9 will advantageously allow rotation of the former within the latter. In my copending application, Serial Number 569,641, filed concurrently herewith, entitled Rotatable Chair Height-Control Mechanism, is shown and described a height control mechanism adapted to provide selective height adjustment of column 8 with respect to tubular hub 9.

While the invention has been described with a certain degree of particularity, this has been for purposes of illustration only, and is not limiting. Rather, numerous changes and rearrangements may be made in the illustrated embodiment without departing from the scope of the invention, as will be apparent to those skilled in the art.

What is claimed is:

1. A chair control mechanism for controlling tilting movement of a chair seat from a horizontal position comprising:

(a) a vertical support column including first mounting means adjacent the upper end of said column and spaced from the vertical axis thereof adapted to horizontally support a pivot pin;

(b) a pivot pin held horizontally by said first mounting means;

(c) second mounting means adapted to be secured to the chain seat and received upon said pivot pin;

(d) control means including a central portion received upon said pivot pin, a first lever arm extending toward the vertical axis of said support column, and a second lever arm extending away from the vertical axis of said support column;

(e) adjustment means comprising a threaded stud fixedly mounted on said second mounting means and means received on said stud and rotatable to vary the axial position thereof along said stud, engageable with said second lever arm of said control means for holding said second lever arm in a selected, fixed position relative to said second mounting means; and

(f) resilient means received in said support column and engaging said first lever arm of said control means to yieldingly oppose tilting movement of said second mounting means.

2. A chair control mechanism as recited in claim 1 wherein said second lever arm includes an apertured end portion, and is longer than said first lever arm; and wherein said threaded stud is received by said apertured second lever arm end portion.

3. A chair control mechanism for controlling tilting movement of a chair seat from a horizontal position comprising:

(a) a vertical support column including a pivot bracket adjacent the upper end of said column and an elongated, vertically aligned, hollow housing, said pivot bracket including a pair of spaced vertical arms defining a first pair of cylindrical apertures aligned in a horizontal axis;

(b) a mounting bracket adapted to be mounted rigidly to the chair seat and including a second pair of spaced vertical arms defining :a second pair of cylindrical apertures aligned in a horizontal axis;

(c) control means including a central portion defining a fifth cylindrical aperture and first and second lever arms extending from said central portion on substantially diametrically opposite sides of said aperture, said second lever arm including an apertured end portion;

(d) a pivot pin extending through said first and second pairs of apertures and through said fifth aperture to pivotally connect said mounting bracket and said control means to said pivot bracket for tilting movement of said chair seat relative to said column;

(e) adjustment means comprising a threaded stud fixedly mounted on said mounting bracket and received by said apertured end portion of said second lever arm, and a handwheel received on said stud and rotatable to vary the axial position of said handwheel along said stud, engageable with said second lever arm of said control means for holding said second lever arm in a selected, fixed position relative to said mounting bracket; and

(f) resilient means received in said housing and engaging said first lever arm of said control means to yieldingly oppose tilting movement of said mounting bracket,

said adjustment means being adjustable for rotating said control means about said horizontal pivot axis relatively to said mounting bracket to change said selected, fixed position and concomitantly to move said first lever arm for adjusting the initial yielding opposition of said resilient means to tilting movement of said mounting bracket.

4. A chair control mechanism as recited in claim 3 wherein said pivot bracket includes a flange portion extending laterally of said vertical support column; said mounting bracket includes a mounting flange portion adapted to be secured rigidly to said chair seat, spaced side portions vertically depending from said mounting flange and including said second pair of spaced vertical arms, an inwardly turned flange at the bottom of at least one of said spaced side portions and an inwardly turned lip adjacent an inward edge of said mounting flange at the rear of said mounting bracket; and wherein said inwardly turned flange of said mounting bracket engages the lower surface of said laterally extending flange portion of said pivot bracket to limit forward tilting movement of said mounting bracket and said inwardly turned lip engages an upper surface of said laterally extending flange portion of said pivot bracket to limit the rearward tilting movement of said mounting bracket.

5. A chair control mechanism as recited in claim 3 wherein said second lever is bifurcated to comprise said apertured end portion.

6. A chair of control mechanism for controlling tilting movement of a chair seat about a horizontal axis comprising:

(a) a support column including a hollow housing portion and means spaced from the axis of the hollow housing portion for receiving and horizontally supporting a pivot pin;

(b) a pivot pin horizontally supported by the pivot pin receiving means, said pivot pin defining the horizontal axis about which the chair seat is tiltable;

(c) a bracket secured to the chair seat and supported upon the pivot pin;

(d) control means fixedly mounted on the pivot pin so as to pivot with the pivot pin, said control means having a first lever arm extending toward the support column and a second lever arm extending away from the support column;

(e) resilient means received in the hollow housing portion of the support column and engaging the first lever arm to yieldingly oppose tilting movement of the chair seat; and

(f) means engaging the second lever arm of the control means for selectively adjusting the position of the second lever arm relative to the bracket so that the position of the first lever arm may be concomitantly varied relative to the resilient means to selectively increase or decrease the initial yielding opposition of the resilient means.

7. A chair control mechanism as defined in claim 6 in which the means for selectively adjusting the position of the second lever arm includes threaded means fixedly mounted on the bracket and rotatable means receivable on the threaded means to vary the axial position of the rotatable means along the threaded means, said rotatable means engageable with the second lever arm so that the position of the second lever arm relative to the horizontal axis may be selected to provide the desired initial yielding opposition of the resilient means.

8. A chair control mechanism as defined in claim 6 in which the bracket includes a pan portion which surrounds and encloses the control means and the means for supporting the pivot pin, said pan portion having a first aperture through which the support column extends and a second aperture through which the adjustment means extends.

References Cited UNITED STATES PATENTS 398,293 2/1899 Tyler 248382 1,247,625 11/1917 Bolens 248378 2,051,043 8/1936 Herold 248378 XR 3,220,688 11/1965 Baermann 248375 XR FOREIGN PATENTS 883,410 7/1953 Germany.

180,474 6/ 1922 Great Britain.

ROY D. FRAZIER, Primary Examiner.

R. P. SEITTER, Assistant Examiner.

. US. Cl. X.R. 

